Hibiscus plant named ‘DUP-SWPK’

ABSTRACT

A new and distinct cultivar of  Hibiscus  plant named ‘DUP-SWPK’, characterized by glossy, dark green leaves, semi-upright habit appropriate for container production and culture, freely flowering habit, and very large pendant double flowers which are uniformly cream pink throughout.

Latin name of the genus and species: Hibiscus rosa-sinensis.

Variety denomination: ‘DUP-SWPK’.

BACKGROUND OF THE INVENTION

The present invention relates to a new and distinct cultivar if Hibiscus, botanically known as Hibiscus rosa-sinensis and hereinafter referred to by the cultivar name ‘DUP-SWPK.’

Hibiscus have been the subject of human admiration for centuries. While the ancestry of present rosa-sinensis hybrids is not be precisely known, todays hybrids are thought to be the products of interspecific crosses involving Hawaiian, Polynesian and Asian species, among others, some of which may no longer be found in the wild, if at all. It is thought that the first hibiscus identified as a “rosa-sinensis” was a double red form of uncertain origin found in cultivation in China, India and Polynesia, to be later introduced to Hawaii from Polynesia. It is known to have been grown in Europe during the Victorian era. Eventually, it was introduced to the continental United States where it was cultivated outdoors in the Deep South as well as in regions having subtropical or Mediterranean climates (Florida and Southern California, respectively). Indoor cultivation took place in the temperate regions of the U.S. It is speculated that the original “rosa-sinensis” is actually a species hybrid, possibly naturally arising, involving two or more species. Regardless, present day hybrids are descended from the original double form, and are thought to include additional species such as Hibiscus liliiflorus, H. arnottianus, H. schizopetalus, and other species, known and unknown, some of which are no longer found in the wild, if at all. Today, after decades of extensive hybridization, the moniker “rosa-sinensis” almost certainly denotes complex interspecific hybrids. Such hybrids are usually far removed from their species ancestors in form and color. Flowers of spectacular size, color intensity and, in the last several decades, ringed and spotted patterns have been produced by U.S. hybridizers primarily in Louisiana, Florida, Texas and elsewhere. Other hotbeds of activity include Australia, and more recently, Tahiti. Today's flowers are removed from their species ancestors to such an extent that it is almost impossible to unravel the species component contributions which comprise a modern hybrid hibiscus.

However, despite the fact that extensive hybridization was giving rise to larger blossoms and more intense colors, few early hybrids attracted the attention of large scale propagators. While the flowers were some of the most impressive in the entire plant world, hybridizer selection for bloom characteristics alone resulted in weak, short-lived plants. Many varieties were difficult to root from cuttings and some only grew acceptably as grafted plants. Grafted plants suffered from a serious disadvantage in that the quality of the graft generally determined the quality of the plant, making the production of uniformly vigorous plants a difficult task. Furthermore, after several years, it was common for grafted plants to develop stresses at the graft union due to the unequal growth rates of the rootstock and the scion. Such stresses can eventually lead to loss of vigor and death of the plant. Moreover, grafting did not completely cure the problem of root rot-surprisingly, the rootstock, when grafted to a root-rot susceptible scion was often more likely to suffer rot than a plant of the rootstock variety. For example, a plant of ‘Seminole Pink’, a garden variety commonly used as a rootstock, is highly resistant to root rot. However, when ‘Seminole Pink’ is used as a rootstock for ‘Romeo’, a modern hybrid which is prone to root rot, the grafted plant, while less susceptible than ‘Romeo’, is more susceptible than a plant of ‘Seminole Pink’. Another disadvantage of grafted plants is the introduction of viruses into the scion from the rootstock. Rootstock varieties are almost invariably old garden varieties which, over the years, have become infected with multiple viruses. While the performance of such vigorous garden varieties may be largely unaffected by the virus infection, the hybrid scion of grafted plants were usually significantly less vigorous than the garden variety rootstock, and virus infection from the rootstock resulted in a weak plant. The problem only increased with successive generations of grafting, resulting in a general weakening of a given variety over time.

As a result, the flower production of many modern hybrids was generally sparse with a high number of deformed blooms. Furthermore, buds often took relatively long times to reach blooming stage, and it was not uncommon to wait with anticipation while a bud swelled day by day, only to be disappointed when the mature bud toppled from its pedicel on the day it was to open. Moreover because of hybridizer emphasis on the flower, the plant was often relatively slow growing and sparsely clothed in leaves.

Such characteristics have left hibiscus with the reputation that, despite the mesmerizing beauty of the flowers, they were for collectors who had time to attend to the seemingly exacting requirements of the plants. As a result, while new varieties were produced by hobbyists yearly, commercial scale propagation of modern hybrids was generally rare. Common garden varieties (‘Seminole Pink’, ‘Brilliant’, ‘President’, ‘Painted Lady’, ‘Butterfly’, ‘Lagos’, and others), which are easy to root, fast growing, and tolerant of a wide range of growing conditions were the only hibiscus widely available.

Many new varieties of hibiscus which represent a vast improvement in rosa-sinensis hybrids, have been produced by an intense hybridizing program conducted by the Inventor at his commercial nursery in Plaquemine, La. The objective of the program has been to produce varieties of hibiscus which root easily under commercial rooting conditions, grow well on their own roots, maturing rapidly into well-leaved, salable plants under commercial greenhouse conditions. Further objectives are to produce hibiscus cultivars as aforementioned, having large flowers with unique and desirable flower characteristics, such as size, color intensity and pattern. ‘DUP-SWPK’ was produced by crossing the cultivar ‘Blue Thunder’ (pollen parent) with the cultivar ‘Gator Pride’ (seed parent). The instant plant was found among the progeny of the stated cross.

Asexual reproduction of the new hibiscus by hard wood, semi-hardwood, and terminal cuttings used in a controlled environment in Plaquemine, La., has shown that the unique features of this new hibiscus are stable and reproduced true to type in successive generations.

SUMMARY OF THE INVENTION

The cultivar ‘DUP-SWPK’ has not been observed under all possible environmental variables. The phenotype may vary somewhat with variations in environment such as temperature, light intensity, nutrition and water status without, however, any variation in genotype. For example, during cooler weather, flowers may demonstrate an increased intensity in pink tones. Furthermore, as with many varieties of Hibiscus, cooler weather can result in a decrease in flower diameter, and a corresponding reduction in size of sepals and pistil. Moreover, as indicated below, plant characteristics vary greatly with culture, with internode spacings often increasing in warmer weather and with higher soil fixed nitrogen content. Plants grown at higher temperatures also exhibit a faster rate of growth. In general the plant used in the following description was grown at temperatures which never dipped below 55° F. Because the Inventor's one gallon pot plants are grown for an average time of about 5.5 to 6 months prior to sale, and the 10 inch pot plants are grown for a average time of about 7 to 8 months prior to sale, it is difficult to provide a precise temperature profile required to give the average plant measurements described in the below description. The growing period can encompass several seasons, with seasonal fluctuations in high/low temperatures as well as photo period. It is expected that the daily high temperature ranged from about 70° F. to about 95° F., and the daily low temperature, which never dipped below 55° F., ranged from about 65° F. to about 80° F.

The following traits have been repeatedly observed and are determined to be the unique characteristics of ‘DUP-SWPK’. These characteristics in combination distinguish ‘DUP-SWPK’ as a new and distinct cultivar.

-   -   1. Glossy, dark green leaves.     -   2. Semi-upright habit appropriate for container production and         culture.     -   3. Freely flowering habit.     -   4. Very large pendant double flowers which are uniformly cream         pink throughout.     -   5. The plant is at least as free-flowering as each parent, and         has been found to root more easily under greenhouse conditions         than either parent.

BRIEF DESCRIPTION OF THE PHOTOGRAPH(S)

The accompanying colored photographs illustrate the overall appearance of the new Hibiscus, showing the colors as true as it is reasonably possible to obtain in colored reproductions of this type.

Colors in the photographs may differ slightly from the color values cited in the detailed botanical description which accurately describe the colors of the new Hibiscus.

The photograph on the first sheet comprises a bloom.

The photograph on the second sheet comprises a double plant of ‘DUP-SWPK’ in a standard nursery gallon pot.

The photograph on the third sheet is of two representative mature leaves of ‘DUP-SWPK.’

The photograph on the fourth sheet comprises a profile of a second day flower demonstrating the proportions of the pistil compared to the bloom diameter. The calyx is clearly visible.

The photo on the fifth sheet comprises the bloom reverse.

DETAILED BOTANICAL DESCRIPTION

In the following description, color references are made to The Royal Horticultural Society Colour Chart except where general terms of ordinary dictionary significance are used. The following observations, measurements, and values describe plants grown in Plaquemine, La., with two plants per 1 gallon container. Plants used for the description were about 24 weeks old.

-   Botanical classification: Hibiscus rosa-sinensis. -   Parentage:     -   -   Female or seed parent.—‘Gator Pride’ (not patented).         -   Male or pollen parent.—‘Blue Thunder’ (not patented).             Commercial Comparison: The instant variety differs from its             seed parent. ‘Gator Pride’ primarily in color, blooming             habit, color pattern and size. The flower is larger,             consistently double, and an even color throughout. The             flower of the instant plant differs from that of the pollen             parent primarily in flower color. The flower differs from             that of other double commercial varieties, such as             ‘Anderson's Double Yellow Red’ and ‘Orange Key’ primarily in             flower color. -   Propagation:     -   -   Type.—cuttings ‘DUP-SWPK’ has been propagated by taking             hardwood, semi hardwood, and tip cuttings, with semi             hardwood preferred. It should be noted that many methods of             asexual propagation, such as tissue culture and other             cloning processes, can be expected to show some degree of             success in the propagation of the present cultivar. However,             of the methods tried by the inventor, the use of semi             hardwood cutting has given the greatest yield of             commercially salable plants. Asexual propagation has             resulted in plants which have the flower and plant             characteristics of the original ‘DUP-SWPK’ plant, and thus             the variety is stable. Cuttings from ‘DUP-SWPK’ generally             root well under commercial greenhouse conditions. While             greenhouse conditions such as relative humidity and other             factors such as cutting age prior to planting affect the             take, it is not unusual to get a take of almost 100%. Please             note that as successive generations of cuttings are raised,             the raiser may experience a drop in take due to the             incorporation of virus, particularly if at some point             grafted plants are prepared, and cuttings are taken from             such a plant.         -   Time to initiate roots.—An average time of initiation at             approximately 22° C. is approximately six weeks, with             slightly longer times during winter at comparable             temperatures, and slightly shorter times during summer at             comparable temperatures.         -   Time to develop roots.—An average time, at approximately 22°             C., of development of a root system after initiation, is             approximately six weeks, with slightly longer times during             winter at comparable temperatures, and slightly shorter             during summer at comparable temperatures. It should be noted             that root initiation and development can be affected by             greenhouse conditions, biological stressors such as disease             organisms, as well as environmental stressors such as low or             variant relative humidity, over- and under-watering,             temperature variations or high or low constant temperatures.             Thus, rooting times can be shorter or longer than the times             given above depending on the values of many different             characteristics during the rooting process known in the art.         -   Root description.—Fibrous and well-branched. -   Plant description:     -   -   Plant form and growth habits.—Perennial evergreen having             upright, rangy, lanky, tall growth. Not generally a compact,             sturdy grower, but internodal space can be dependent upon             greenhouse temperature time profile, fertilizer time             profile, and other factors.         -   Branching habit.—Only moderately well-branched, having             approximately 1-2 laterals when a single stem plant is             pinched back to a 5 inch height.         -   Plant height, soil level to top of flowers.—A salable plant             (having 2 separate plants) in a 1 gallon nursery pot can be             approximately 24 inches high and 24 inches wide. Please note             that cultural variables such as greenhouse temperature time             profile, fertilizer level, and other factors can cause             significant variation from the values given herein.         -   Lateral branch description.—The average branch             characteristics of a salable 1 gallon plant: Average Length:             Approximately 15″. Average Diameter: Approximately 0.8 cm             measured at the transition from green to woody stem texture.             Texture: Immature, smooth; mature, woody and rough. Color:             Immature: Green, more green than 147A. Mature: Brownish             gray, close to 200C with 197A overtones. -   Mature Foliage description:     -   -   Arrangement.—Alternate, single; numerous; symmetrical.         -   Length.—Approximately 12.4 cm.         -   Width.—Approximately 10.1 cm.         -   Shape.—Ovate.         -   Apex.—Acute.         -   Margin.—Crenate.         -   Texture.—Glabrous, rugose.         -   Color.—Young foliage, upper surface: More green than 147A;             very glossy. Mature foliage, upper surface: Generally darker             than 147A; glossy.         -   Petiole.—Average Length: 3.1 cm. Average Diameter: 0.3 cm.             Texture: Fine pubescence on upper surface; lower surface,             glabrous. Color: Dark greenish brown; close to 200A with             undertones of 147A. It should be noted that as with other             plant growth characteristics foliage color and size can vary             somewhat with fertilization regimen, greenhouse temperature,             daylength, and other conditions of culture. -   Flower description:     -   -   Natural flowering season.—Year round, with number and size             reduction in extended periods of cold weather, such as             daytime temperatures of less than 60° C. Extreme heat can             slow growth and flower production.         -   Flower arrangement.—Flowers arranged singly at terminal leaf             axils. Very free-flowering, with usually about two or three             developing flower buds per lateral branch, flowers are             mostly pendant.         -   Flower appearance.—Large, rounded single flowers. Flowers             are open for one to two days before senescence, which is             often accompanied by partial or full petal closure. Flowers             persistent.         -   Flower diameter.—DUP-SWPK flowers are generally in the range             of from about 8-9″ when fully open, with largest flowers             produced during warm weather (for example, day and night             time temperatures above 73 degrees F.         -   Flower depth.—Flower depth was measured to average             approximately 2 cm. Flower depth was measured after removal             of a petal and a sepal to expose the base of the pistil. The             measurement was taken on a fully opened flower in the             direction of the pistil, from the base of the ovaries to the             maximum height of the flower petal, which is the point of             recurvature of the petal. It should be noted that hibiscus             blossoms can flatten out during the day, or increase or             decrease in curvature or degree of petal reflex during the             day, and thus variance from the foregoing value is possible.         -   Flower bud (just before showing color).—Rate of opening: 1-3             days. Rate of opening is generally faster in warmer weather.             Flower bud dimensions were measured on a bud which was             approximately two days from opening. The measurements were             as follows. Bud length was measured from the abscission zone             where bud and peduncle meet to the tip of the bud. The             average length of a bud which is one day from opening is             approximately 9.8 cm. Bud diameter was measured at the             widest part of the bud, an area approximately halfway up the             outside of the developing petals. The average diameter of a             bud which is one day from opening is approximately 2.9 cm.             It should be noted that bud dimensions can vary somewhat             with cultural conditions, and variations can even be             observed in buds which are at the same stage of development.             Shape: Elliptic. Color: More green than 147A.         -   Petals.—Texture: Smooth, satiny, rugose. Arrangement: The             corolla consists of five petals arranged in a whorl, having             regular partial overlap, even when the flower is fully open.             Flowers comprise a doubling ruff of petal tissue, largely or             entirely originating from staminal column tissue. Shape:             Roughly spatulate, with a rounded apex and a truncate base.             The margin of each petal undulate and entire. Petals can be             strongly recurved, with little overlap when flower is             entirely open. A representative length was measured to be             8.5 cm, and was taken from the base of the petal to the             farthest point on the margin opposite the base. A             representative width is 8.4 cm, and was measured             perpendicularly to the pistil at the widest point of the             petal. Petal size can vary with cultural conditions, such as             temperature, and thus the flower size and shape can vary as             well. Often, flowers which are produced at colder             temperatures are smaller and appear more fully overlapped.             When fully open, the edges of DUP-SWPK flowers often recurve             stiffly. The color of a warm weather flower is described             below. It has been observed that colder temperatures can             result in the stronger expression of pink tones in the             petals. It should be noted that the colors of hibiscus are             among the most changeable of all flowers. A newly opening             morning bloom generally has the most intense coloration, but             as the flower flattens out and is exposed to the sun, many             pigments begin to fade immediately, resulting in a flower             which can look like a different variety altogether. Unlike             many hibiscus varieties of stronger coloration, the flowers             of DUP-SWPK fade relatively little by the second day, with             the flower generally only taking on a translucent cast. The             morning colors are described below. Color: Upper surface:             Margin: 56D. Center: 56D. Base: 56D. Lower surface: Left             side: 11C. Right side: 11D.         -   Sepals.—Unlike the petals, sepals are relatively invariant             in color. Their size can be affected by same cultural             conditions which affect flower size, They are generally             smooth and elongated oblong with acute apices (pointed             tips). They are fused at the long edges into a cupped calyx             bearing at its brim the five pointed tips. When the petals             of the flower spread open, the five pointed tips, which are             flush with the backs of the opening petals, are forced into             a radiating five point star-shaped configuration, which can             be observed on the profile and reverse pictures. A             representative width, which is measured perpendicularly to             the long axis of the sepal a at the position on the sepal at             which the oblong edges transition from fused to unfused, is             approximately 1.3 cm. A representative length, measured on             the sepal from the free point to the fused point is             approximately 3.1 cm. Color: Upper surface: Close to 146A.             Lower surface: Close to 147A.         -   Peduncle.—Length: 5.8 cm. Angle: Approximately 35 degrees             from branch. Strength: Strong, flexible. Texture: Smooth.             Color: Slightly darker than 146A.         -   Reproductive organs.—Androecium: Stamen number:             approximately 75. Anther shape: Crescent. Anther color: 11D.             Amount of pollen: Moderate. Pollen color: 23B. Gynoecium:             Pistil number: 1. Pistil length (from base of ovaries to top             of stigma): 7 cm. Style length (from base of ovaries to             stigma branching point): 6.2 cm. Style diameter, at base:             1 cm. Style color: Base: 11C. Midsection: 12C. Apex: 11D.             Stimga number: Often 5, but can vary. Stigma color: 45C.

It should be noted that the dimensions of a hibiscus blossom generally change not only during bud development, but also during opening, as well as during the life of the opened flower. For instance, upon opening, the petals generally gain in length. Double varieties gain significant mass during opening. Furthermore, after opening, the pistil continues to grow in length while the anther filaments which hold the pollen sacs increase in length, the pollen sacs open and the stigmas separate, each at the tip of a branched style structure. Toward the end of the flower life, possibly due to a reduction in turgor pressure, the pistil may shrink in length and the petals may slightly decrease in area. Usually, the senescing petals of the flower fold toward the pistil to some degree, in some cases, completely enfolding it.

Furthermore, the present variety DUP-SWPK is capable of producing a range of flower forms, from semidouble, to full double. Because the “doubling” is usually due to the conversion of sexual flower segments, such as anther tissue, and less commonly, pistil and stigma tissue, to petal tissue, the degree of doubling has an effect on the number of reproductive segments exhibited by such a flower. For example, a fully double flower can have a greatly reduced number of anthers with respect to a single flower. Even if the doubling has not effected the conversion of stigma tissue into petal tissue, the effect of doubling on the stigmas is often to deform the staminal column to such an extent that the stigma are buried in petal or column tissue and are either under-developed or impossible to locate, and in some cases, completely absent, with only the pointed style branches remaining as the flower's attempt to express female flower segments. Another phenomenon which is observed in hibiscus flowers which exhibit a high degree of doubling is the occasional production of multiple pistils, most often fused at the base or along their lengths. Usually, such fusion results in pistils which are incomplete, but the potential for multiple pistils, and thus supernumerary anthers and stigmas exists with double hibiscus in general, and the present variety, DUP-SWPK, in particular.

Seeds are not typically produced and are unlikely to be observed under most growing conditions.

-   Disease resistance: ‘DUP-SWPK’ has not been observed to be resistant     to pathogens common in hibiscus. However, it has been observed in     the green house to have a higher resistance to root rot than that of     many existing hybrid varieties grown on their own roots known to the     Inventor. If desired, and if a risk of virus infection is of no     concern, the present variety can be grafted onto a rootstock and be     grown as a grafted plant. 

It is claimed:
 1. A new and distinct hibiscus plant named ‘DUP-SWPK’, as illustrated and described. 